Light-sensitive photographic emulsion



March 27, 1951 w. K. A. KOERBER ET AL 2,546,542

LIGHT-SENSITIVE PHOTOGRAPHIC EMULSION Filed April 28, 1947 MLLEM KAREL ANTOON KOERBER Desma MAizaA ALoyslus VAN G'OETHEM Agen Patented Mar. 27, 1951 UNITED STATES PATENT OFFICE LIGHT-SENSITIVE PHOTOGRAPHIC EMULsIoN Willem Karel Antoon Koerber, Berchem-Antwerp, and Dsir Maria"` Aloysius Van G0eth`em-,= Kontich, Belgium, assignors to'Gevaert Photo- Producten N.A V., Mortsel-Antwerp, Belgium, .a

company of Belgium- Application April 28, 1947, Serial N0. 744,522` In Germany September 5, 1941 Section 1, Public Law 690, August 8, 1946- Patent expires September' 5, 1961 6 Claims.

This invention relates to light-sensitive photographic silver halide emulsions, and more particularly to such emulsions oi increased "color sensitivity.

The primary object of our invention is to provide J- an* improved light-sensitive photographic z silverhalide emulsion.

A- more specic object is, to provide a lightsensitive photographic emulsion having a supersensitizing quality. It is known to increase the spectral sensitivity of a photographic emulsion by simultaneously using a sensitizing dyestuihwhich'.

is'called main sensitizer, and a second' sensitizing dyestui called supersensitizer. simultaneously using carbocyani es and pseudocyanines, the general sensitivity of the emulsiony is much higher than it would be theoretically by themere additional action of a sensitizer. In the photographicart,l such an increase in spectral` sensitivity is known as supersensitzing.`

A stillmore particularized object is to provide a light-sensitive photographic emulsion containing a supersensitizing combination of a styryl dye and an organic compound of the kind `disclosed hereinafter.

Further objects oi the present inventionare toprovide a method of increasing the sensitivity of. photographic emulsions sensitized with styryl' dyes, a process for sensitizing photographic einnisions with a supersensitizing combination of a styryl dye and said organic compound disclosed.

further below.

A still further object is to provide a photographic element comprising a support coated with lsuch a supersensitiaed emulsion.

Other more speciiic objects will become apparent duringfthe persual oi this.specification.

It is known to use styryl compounds for the.

optical senstizing of photographicy silverhalide emulsions.

rThough the supersensitizing action is generally .obtained by the combined use of two or more dye- -stuffs, it has already. been proposed to accomplish the supersensitizing effect bythe use of ,special cyanine dyestufls in combination with non-sensitizing organic compounds containing an amino group.

Unexpectedly, we have found that the color sensitivity of lphotograpl'lic emulsions sen'sitizt-:dl

byrm'eans of styryl compounds may be increased For instance; by

to an extraordinary extent .bythe addition to thev X represents alkyl or hydrogen; and X represents alkyl.

The present invention enables-the supersonsitizing of both silver chlorideand silver bromide emulsions sensitized by styryl compounds, improving sirnultaneousiy the stability thereof As the main sensitiaer all styryl dyestuiis may*7 beused .which correspond to the following gen eral formula:

D representsnon-metallic atoms necessary to complete a heterocyclic 5- or o-membered ring;

' R represents alkyl, aryl or aralkyl;

X represents halogen or. any acid residuegand n represents a-positive integer:

Rl N represents res1dues of secondary amines, for mstance,

\ 2- p-dimethylamino-styryl-quinoline etliiodide,

R 2-p-dimethylamino-styryl-bcnzthiazol inethiodide,

2-p-dimethylamino-styryl-beta-naphthothiazole-mctbiodido 2-p-dimethylamino-styryl-4-1netliyl-thiazole,ethiodidel 2-pV-d1methylaminostyryl-benzoxazolc benzyl bromide. According to the present invention, products capable of increasing the activity of these dyestuis are, for instance, the following;

NH-o o-oH-CEn-ornv Alpha-mercapto-n-butyric acid naphthyl amide SHv Alphmmencapto-.propionic :acid:p-itoluldide4 Alpha-mercupto-iso-valeric acid p-chloroanilide Alpha-mercapto-iso-butyric acid p-toluidde The preparation of these supersensitizers is described in Beckurts and Frederichs, Archiv der Pharmazie 253, page 161.

To carry out the method of the present invention, the main sensitizer and supersensitizer may simultaneously be added to the emulsion; or the coated light-sensitive emulsion already containing the main sensitizer may be bathed in a solution of the supersensitizer; or the non-sensitized emulsion layer may be bathed in a mixture of the two sensitizers. Finally, the supersensitizer may be added to the anti-stress layer or to the barite layer.

The light-sensitive emulsion may be prepared with the help of any binder known in the photographic emulsion technique, e. g., gelatine and vinylpolymers.

The method of our invention is illustrated by the following specic example:

A silver chloride emulsion according to Eder Handbuch III, 5th edition, i993, page 727, is prepared in the following way:

(A) 15 g. of sodium chloride,

l g. of citric acid, 20 g. of gelatine 200 cm.3 oi water; (B) 30 g. of silver nitrate,

50 cm.3 of water; (C) 20 g. of gelatine,

250 cm.3 of water.

(A) and (C) are melted at 45 C., (C) is added to (B) whilst stirring, and immediately afterwards (A) is added to (B) -i-(C). Next, 2 ein.3 oi a 0.1% 2 p dimethyl'amino styryi 4 methyl thiazole ethiodide solution are added and this mixture is allowed to ripen for one hour. Thereupon 4 0111.3 of an alcoholic solution of a 1 mercaptobutyric acid-p-toluide solution are added, and after l5 minutes the emulsion is cast. The sensitivity of this emulsion is illustrated by the accompanying drawing which is self-explanatory.

It will be apparent that while we have described our invention in preferred forms, many changes and modifications may be Ina-de without departing from the spirit o the invention dened in the following claims.

We claim: v

1. A light-sensitive photographic silver halide emulsion containing as a sensitizer 2-p-dimethylamino-styryl-i-methyl-thiazole ethiodide and as a supersensitizer alpha-rnercapto-iso-butyric acid p-toluidide. Y

2. Light-sensitive photographic silver halide emulsion containing at least one sensitizing dyestuf corresponding to the general formula:

D represents the non-metallic atoms necessary to complete'a member selected fro-m the group consisting of heterocyclic 5-nie1nbered and heteiocyclic -membered rings,

R. represents alkyl, aryl, aralkyl,

R and R" represent alkyl,

X represents a member selected from the group consisting of halogen and an acid residue, and

n represents a positive integer,

and as a supersensitizer at least one product of the general formula:

wherein Y represents aryl, X represents a monovalent group selected from the group consisting of alkyl and hydrogen, and X represents an alkyl group.

3. Light-sensitive photographic silver halide emulsion containing at least one sensitizing dyestuff corresponding to the general formula:

and as a supersensitizer alpha-mercapto n-butyric acid naphthyl amide.

4. Light-sensitive photographic silver halide emulsion containing a sensitizing ,dyestui corresponding to the general formula:

D represents the nonnetallic atoms necessary-to complete a member selected from the group consisting of heterocyclic -membered and het-` erocyclic -membered rings,

R represents alkyl, aryl, aralkyl,

R and R represent alkyl,

X represents a member selected from the group consisting of halogen and an acid residue, and

n represents a positive integer,

and as a supersensitizer alpha-mercapto propionic acid-p-toluidide.

5. Light-sensitive photographic siiver halide emulsion containing a sensitizing ,dyestuif corref spending to the general formula:

D represents the non-metallic atoms necessary to complete a member selected from the group and as a supersensitizer alphamercapto-iso valerio acid p-chloroanilide.

G. Light-sensitive photographic silver halide emulsion containing a sensitizing .dyestu corresponding to the general formula:

D represents the non-metallic atoms necessary to 20 complete a member selected from the group 6 consisting of heterocyclic -membered and heterocyclio -rnembered rings,

R represents alkyl, aryl, aralkyl, R and R represent alkyl, X represents a member selected from the group consisting of halogen and an acid residue, and n represents a positive integer,

and as a supersensitizer alpha-mercapto isobutyrc acid p-toluidide.

WILLEM KAREL ANTooN KOERBER. DSIRE' MARIA ALOYSIUS VAN GOETHEM.

REFERENCES CITED UNITED STATES PATENTS Name Date Mees Mar. 30, 1937 Number 

2. LIGHT-SENSITIVE PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING AT LEAST ONE SENSITIZING DYESTUFF CORRESPONDING TO THE GENERAL FORMULA: 